Electronic Assembly Process Technology
Modern electronic assembly technology includes PCBA assembly process and complete machine assembly process. Among them, the PCBA assembly process is also called board-level assembly, which refers to the assembly technology of installing and soldering components to the specified positions on the PCB board. It can be divided into multiple processes such as component pre-forming, wave soldering, reflow soldering, milling, potting, conformal coating, and functional testing.
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![Solder Paste]()
Solder PasteSolder Paste Product Line Solder paste may seem inconspicuous, but it directly determines whether the soldering quality is good or not. Cold solder
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![Tin Solder]()
Tin SolderSolder Materials We've been making microelectronic soldering materials for over twenty years. Our solder product line includes solder wire, sol
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![Flux]()
FluxFlux Solutions Our company has been making flux for over twenty years, starting from 1998. We're among the first batch in China to
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![Cleaning Agent]()
Cleaning AgentCleaning Agents Cleaning Agents are formulated using a composite surfactant, penetrating agent, degreasing agent, and corrosion inhibitor blendin
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![Conformal Coating]()
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![Adhesive]()
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![Thermal Conductive Materials]()
Development History
Modern electronic assembly technology was developed in the mid-1960s and was widely applied in the 1970s, especially SMT. As a new type of electronic assembly technology, due to its characteristics of high component assembly density, good reliability, low production cost, and ease of automation, it has developed rapidly since the 1980s. SMT surface mount technology has powerfully promoted the development of modern electronic industry.
Interdisciplinary Field
Modern electronic assembly technology has a wide scope and includes much content; it is a high-tech interdisciplinary field. It contains core processes such as surface mount components, PCB substrates, surface mount pattern design, surface mount equipment, surface mount process methods, surface mount process materials, surface mount testing, and surface mount technology management. These aspects are mutually restrictive and mutually influential, constituting indispensable parts of the overall modern electronic assembly technology.
Commonly Used Materials in Modern Electronic Assembly
The development history of the electronic industry proves that electronic materials are closely related to electronic technology and are the premise and foundation for developing the electronic industry, and an important component of contemporary high-tech fields. In the development process of electronic assembly technology, electronic chemical materials similarly play a quite important role.
Currently, there are numerous types of chemical materials related to assembly processes, including various base materials used in PCB manufacturing, solder mask inks, pre-applied flux, hot air leveling flux, etc.; there are also photoresists, high-purity reagents and gases used in component and integrated circuit production, as well as various packaging materials, etc.
Development History
Modern electronic assembly technology was developed in the mid-1960s and was widely applied in the 1970s, especially SMT. As a new type of electronic assembly technology, due to its characteristics of high component assembly density, good reliability, low production cost, and ease of automation, it has developed rapidly since the 1980s. SMT surface mount technology has powerfully promoted the development of modern electronic industry.
Composition of Auxiliary Materials for Electronic Assembly
(1) Definition of Auxiliary Materials for Electronic Assembly
In the electronic product assembly process, process materials that play an auxiliary operational role, such as: solder, flux, solder paste, adhesive (red glue), UNDERFILL adhesive, structural adhesive, thermal conductive adhesive, cleaning agents and various solvents (anhydrous ethanol, industrial ethanol, isopropanol), etc., are collectively referred to as auxiliary materials for electronic assembly.
(2) Role of Auxiliary Materials for Electronic Assembly
The various auxiliary materials used in the electronic product manufacturing process are all selected by process design to meet certain process purposes during the product manufacturing process. Unlike the materials selected during product design, such as: metallic, insulating and other structural materials, traces of them can almost all be seen retained in the finished manufactured product. The auxiliary materials selected in process design are different; they can roughly be divided into the following two major categories.
① Permanent Traces
Those that can permanently leave traces in the final finished product: such as solder (including solder paste) and various adhesive materials, etc.
In the product interconnection process, through metallurgical reactions with substrate materials or physical-chemical adhesion, they constitute indispensable and extremely important structural materials in various joint parts. Every electronic product system is invariably firmly interconnected through solder connecting various kinds of thousands upon thousands of electronic components. It can be said: without solder there would be no modern various electronic equipment, and human society would not have today's civilization.
② No Traces
Those that will not leave any traces in the final finished product: such as flux, cleaning agents, high-temperature adhesive tape, etc.
These materials are crucial for the process but are removed or evaporate, leaving the final product clean and reliable.
Key Material Categories
Solder Paste
Core material used in SMT surface mount technology, composed of alloy powder mixed with flux, applied to PCB pads through printing or dispensing methods, achieving reliable connection between components and circuit boards through reflow soldering.
Solders
Including forms such as solder wire and solder bar, widely used in wave soldering, manual soldering and rework processes. Provides lead-free and leaded alloy formulations to meet different soldering temperature and reliability requirements.
Flux
Used to remove metal surface oxides, reduce surface tension, and improve solder wettability and flowability. Covers multiple types including no-clean, water-soluble and rosin types, adapting to different process requirements.
Cleaner
Specialized for removing post-soldering flux residues, oil contamination and particulates, ensuring PCB surface cleanliness. Includes water-based, semi-aqueous and solvent-based products, balancing cleaning effectiveness with environmental compliance.
Conformal Coating
Provides moisture-proof, salt spray-proof and mildew-proof protective coating for circuit boards, effectively isolating harsh environmental corrosion, extending electronic product service life, widely used in automotive, aviation and outdoor electronic equipment.
Adhesive
Covers SMT red adhesive, underfill adhesive, structural adhesive, etc., used for component fixation, chip encapsulation and structural bonding, providing excellent mechanical strength, heat resistance and electrical insulation performance.
Thermal Conductive Materials
Including thermal grease, thermal pads, phase change materials, etc., used to fill gaps between heating elements and heat sinks, efficiently conducting heat, ensuring stable operation of electronic equipment.
Development Trends of Modern Electronic Assembly Materials
The development of electronic assembly technology requires new process materials to adapt to it, while the development of new process materials further promotes the development of assembly technology. Assembly process materials must meet the needs of the rapid development of assembly technology.
Stability and Reliability
Starting from the requirements of high product performance and high quality, modern electronic process materials should have good stability and reliability. For mounting adhesive, its strength should be neither too high nor too low, ensuring no component loss during the soldering process while facilitating component replacement during maintenance; for solder, strict control of harmful impurity content is required; for flux and solder paste, low residue and non-corrosiveness are required, while some military products still require cleaning after soldering.
Mass Production and Speed
Starting from the requirements of mass production, assembly process materials are required to meet high-speed needs. The development of mounting adhesive is the most concrete example. In the mid-to-late 1980s, most mounting adhesives used oven batch curing, with typical curing conditions of about 150°C for 20 minutes, while by the 1990s tunnel oven continuous curing gained dominance, requiring mounting adhesive to cure within 5 minutes at 150°C, and more recently requiring curing within 1-2 minutes.
Fine-pitch Assembly
With the development of fine-pitch assembly, higher assembly density is required. For alloy solder powder in solder paste, finer particle size is required, and better thixotropy and smaller slump are required for solder paste and mounting adhesive. Strict control of solid content and activity in flux is necessary to avoid poor soldering phenomena such as bridging.
Environmental Protection
Beneficial to environmental protection and human health. With increasingly loud calls for protecting the atmospheric ozone layer, no-clean and water-clean flux or solder paste have been vigorously developed, while multiple cleaning agents with no destructive effect on the atmospheric ozone layer have also been developed. From the purpose of protecting the environment and human health, VOC-free (volatile organic compound) no-clean flux and solder paste have recently been developed. To eliminate the toxic harm of lead to the human body, multiple lead-free solders have been developed in recent years, which currently remains the main direction of solder research and development.
Integration and Heat Dissipation
Modern communication electronic products are also developing toward integration, with integrated chips and high-power devices being applied in large quantities, which has also raised higher requirements for product heat dissipation methods and materials. New thermal conductive materials have also emerged in endless streams during this period. The appearance of high thermal conductivity ultra-soft thermal pads, high thermal conductivity low-viscosity thermal adhesives, phase change materials, graphene thermal conductive materials, etc., has also emerged in response to the development of assembly technology.